The present invention is designed as a new and useful improvement to the invention disclosed in U.S. Pat. Nos. 5,472,672, and 5,529,756, and applications Ser. Nos. 08/452,967 and 08/453,972 (still pending) to Brennan which had provided an Apparatus and Method for Polymer Synthesis Using Arrays. The disclosures of these U.S. Patents and pending applications are incorporated herein by reference and will be herein collectively referred to as "the existing Brennan system."
In the existing Brennan system, various reagents were sequentially added to various reaction wells which were laid out in an array of columns and rows. This array of reaction wells was moved back and forth in a direction parallel to these rows by a transportation mechanism with stationary nozzles for dispensing these reagents positioned in a corresponding array of columns and rows above these reaction wells. These nozzles were connected by tubing to the various reagents and valves were selectively opened and closed as desired allowing the various reagents to pass into these various reaction wells. By moving this array of reaction wells back and forth under this stationary array of selectively opening nozzles, the various reagents were added in various sequences and combinations to the different reaction wells.
In the existing Brennan system, each of the particular reagents to be delivered were typically connected to all of the nozzles in a particular column of nozzles in the nozzle array, and the array of reaction wells was then moved back and forth in a direction parallel to the rows of reaction wells passing under these various columns of nozzles. Using this setup, each reagent could be delivered into any reaction well positioned therebelow. Unfortunately, using this particular setup for synthesis of polymers by sequentially adding various reagents into these various reaction wells was therefore limited in the actual number of reagents it was able to simultaneously utilize because all of the nozzles in each particular column of nozzles were connected to dispense the same reagent. The number of reagents which could be utilized was therefore limited by the number of columns of dispensing nozzles. Alternatively, other setups could conceivably be adapted where the various nozzles in any particular column or columns of nozzles could be connected to dispense different reagents. Unfortunately, all these alternative setups have the limitation that the various nozzles in a particular column of nozzles would not be able to dispense different reagents such that all of the various individual reaction wells in the reaction well array could be positioned so as to receive each of the various reagents being dispersed. This occurs because each row of reaction wells is movable back and forth under only one nozzle in each column of dispensing nozzles. The existing Brennan system is therefore limited in that all of the reagent dispensing nozzles cannot be aligned with all of the reaction wells. Rather, each single row of reaction wells can only be aligned with a particular single row of dispensing nozzles in the nozzle dispensing row positioned thereabove. In addition, the existing Brennan system was limited in that it was directed mainly to specific oligonucleotide polymer synthesis with limited numbers of reagents and not specifically to synthesizing other sorts of chemicals such as small molecule pharmaceuticals.
The present invention improves upon the existing Brennan system to provide the advantages of greater flexibility and a vastly increased number of reagents or other chemical units which can be simultaneously used in the synthesis of all types of chemicals. This invention also provides a method and apparatus for chemical synthesis sequentially adding reagents or other chemical units to an array of reaction wells in which a much greater number of different and more complex compounds can be simultaneously synthesized therefrom.